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Date: Wed, 29 May 2024 14:39:33 +0300
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Subject: Re: [PATCHv11 06/19] x86/kexec: Keep CR4.MCE set during kexec for TDX
 guest
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
 Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
 Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>,
 x86@kernel.org
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
 Peter Zijlstra <peterz@infradead.org>,
 Adrian Hunter <adrian.hunter@intel.com>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>,
 Elena Reshetova <elena.reshetova@intel.com>,
 Jun Nakajima <jun.nakajima@intel.com>,
 Rick Edgecombe <rick.p.edgecombe@intel.com>,
 Tom Lendacky <thomas.lendacky@amd.com>, "Kalra, Ashish"
 <ashish.kalra@amd.com>, Sean Christopherson <seanjc@google.com>,
 "Huang, Kai" <kai.huang@intel.com>, Ard Biesheuvel <ardb@kernel.org>,
 Baoquan He <bhe@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
 "K. Y. Srinivasan" <kys@microsoft.com>,
 Haiyang Zhang <haiyangz@microsoft.com>, kexec@lists.infradead.org,
 linux-hyperv@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org
References: <20240528095522.509667-1-kirill.shutemov@linux.intel.com>
 <20240528095522.509667-7-kirill.shutemov@linux.intel.com>
From: Nikolay Borisov <nik.borisov@suse.com>
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In-Reply-To: <20240528095522.509667-7-kirill.shutemov@linux.intel.com>
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On 28.05.24 г. 12:55 ч., Kirill A. Shutemov wrote:
> TDX guests run with MCA enabled (CR4.MCE=1b) from the very start. If
> that bit is cleared during CR4 register reprogramming during boot or
> kexec flows, a #VE exception will be raised which the guest kernel
> cannot handle it.
> 
> Therefore, make sure the CR4.MCE setting is preserved over kexec too and
> avoid raising any #VEs.
> 
> The change doesn't affect non-TDX-guest environments.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>